BI02 Disseminated toxoplasmosis presenting as panniculitis in an immunocompromised patient
Authors: Sylvia Huang, Jeva Cernova, Diana Mabayoje, Raj Thuraisingham, Filipa Barroso, Catherine Harwood, Marcin Ligaj
Journal: British Journal of Dermatology (2023)

Abstract Inflammatory dermatoses and inflammatory reaction patterns to underlying systemic disease are relatively uncommon in immunosuppressed organ transplant recipients (OTRs) and infection should always be suspected as a possible cause. We present an OTR with biopsy-proven panniculitis resulting from disseminated toxoplasmosis, only identified after extensive histological analysis. A 45-year-old Nigerian woman who was profoundly immunocompromised through a combination of a kidney transplant 12 months earlier, hyposplenism due to sickle cell anaemia and a CD4+ count 74 × 106 cells L–1 (&amp;gt; 455 × 106 L–1) presented with a 3-month history of &amp;gt; 20 painful, red–purple and hyperpigmented subcutaneous nodules and plaques up to 2 cm in diameter limited to her legs, associated with fatigue and weight loss. She only had childhood contact with cats. There was no lymphoedema or lymphadenopathy, and she was HIV negative. Urgent skin biopsy excluded Kaposi sarcoma and demonstrated a lobular, necrotizing panniculitis, a mixed inflammatory cell infiltrate and evidence of vasculitis. The cause was unclear; cultures for mycobacterial, fungal and bacterial infections were negative. However, on rereview of histology, within areas of inflammation and necrosis in the subcutaneous fat, there were a few scattered structures (10–30 μm in diameter) consisting of small basophilic periodic acid–Schiff-positive ‘dots’ within bright eosinophilic cytoplasm, raising the possibility of toxoplasmosis. Toxoplasma immuno­staining was positive. Further tertiary review of histology and immunostaining by the Hospital for Tropical Diseases agreed that there was no other causative organism and the panniculitis and vasculitis were consistent with active toxoplasmosis. The diagnosis of toxoplasma reactivation was supported by positive toxoplasma IgG on pretransplant bloods. Magnetic resonance imaging of the head was consistent with cerebral toxoplasmosis. She received treatment with clindamycin, pyrimethamine and folinic acid and, thereafter, long-term cotrimoxazole prophylaxis. Cutaneous toxoplasmosis is rare, with only three reported cases over the last 10 years. Historically, a wide spectrum of clinical morphologies has been described, including maculopapular rashes, nodules, ulcers, dermatomyositis and even mimicry of varicella and graft-versus-host disease. Most cases affect immunocompromised patients. In our patient, this was the result of reactivation of latent infection, which is more common in West Africa, coinciding with profound immunosuppression. In our case, a diagnosis was only made after extensive histological review. Given the varied morphologies of clinical presentations, it is possible that this condition may be easily missed, with potentially serious consequences. In summary, we highlight the importance of maintaining a high index of suspicion for infection and the need for careful clinicopathological correlation in OTRs presenting with apparently atypical inflammatory skin lesions.